Pumps



S. P. HUTTON Nov. 22, 1966 PUMPS 2 Sheets-Sheet 2 Filed July 23, 1963 ATTORNEY:

United States Patent 3,286,639 PUMPS Stanley Peerman Hutton, Cardiff, Wales, assignor to BSA. Harford Pumps Limited Filed July 23, 1963, Ser. N0. 297,006 Claims priority, application Great Britain, July 24, 1962, 28,402/ 62 11 Claims. (Cl. 103-41) This invention relates to centrifugal pumps.

In accordance with .a feature of the invention a centrifugal pump is provided with a by-pass, and the bypass flow is returned to the inlet of the pump in counter flow to the main flow through the inlet, in order to restrict the said main flow.

With this arrangement, the variation in the pump output which would normally result from the provision of a by-pass is augmented by using the flow from the bypass to restrict the main flow into the pump by producing an additional throttling action.

Other features and advantages of the invention will appear from the following description of a pump in accordance therewith, the pump being illustrated in the accompanying drawings, in which:

FIGURE 1 is an axial section of the pump;

FIGURE 2 is a section on the line A-A of FIGURE 1; and

FIGURE 3 is a partial section on the line B-B of FIGURE 1.

The particular pump illustrated in the drawings is of the sleeved-gap motor driven type, and is primarily intended for use as the circulating pump of a central heating system. The motor section of the combined motor pump unit is not illustrated since it may be of conventional construction and forms no part of the present invention.

The pump comprises a cast body 1 having an inlet 2, an outlet 3 and a volute 4 housing an impeller 5, and as so far described is of conventional construction.

The volute 4 of the pump is connected with the inlet by means of a by-pass passage 10, formed in the pump body, the passage having its entrance positioned half way round the volute 4 and making an angle of approximately 15 with the axis of the inlet 2. The mass flow through the bypass passage is controlled by means of a rotary valve 11 formed with an elongated aperture or port 12. The valve is rotatably supported in the body 1 and carries at its outer end a knob 13 by means of which the valve can be manually rotated to vary the minimum effective cross sectional area of the port 12, and therefore of the by-pass passage 10.

In operation of the pump, with the valve 11 in its illustrated position, part of the flow in the volute is bled-off by the by-pass 10 and is discharged into the flow through the inlet 2. The by-pass flow is in counter flow to the main flow through the inlet, in that the bypass discharge has a component of momentum which opposes the inlet flow and therefore tends to reduce the mass flow through the inlet. By rotating the valve anti-clockwise from its illustrated position in FIGURE 1, the flow through the by-pass 10 is progressively decreased, so that the bypass discharge exerts a progressively reducing opposition to the inlet flow, until finally, the passage 10 is completely shut, there is no by-pass flow, and the inlet flow is a maximum. Simultaneously with the reduction in mass flow, rotation of the valve alters the angle, relative to the direction of the main flow through the inlet, at which the by-pass flow discharges into the inlet, so that the opposition to the main flow exerted by the by-pass flow is reduced.

In this way, the performance of the pump can be varied so that the pump can operate over a wide range "ice of head and mass flows with the same impeller and with a constant speed.

Although it is at present preferred to arrange for both the mass flow through the by-pass passage 10 and the angle at which the by-pass discharges to be made variable, it may, in some cases be desired to arrange for the flow through the by-pass to be controlled by a two-position, on-off valve, either in combination with the by-pass discharge angle being either fixed or variable. Again, the angle could be fixed and the mass flow variable. It may even be desired in some cases to provide a by-pass passage with a fixed angle and fixed flow, for the purpose, for example for altering the performance of an existing pump.

It will be seen therefore that many variations are possible in the described embodiment of the invention, without departing from the scope of the appended claims.

I claim:

1. A centrifugal pump comprising a pump housing defining therewithin a volute chamber, an inlet duct for a main flow of fluid to said volute chamber and an outlet duce from said volute chamber, said housing further defining a by-pass passage connecting said volute chamber with said inlet duct, and pump means within said volute chamber for pumping fluid through the housing, said bypass passage being oriented to direct the by-pass flow into the inlet duct substantially in opposition to the flow in said duct and at an acute angle thereto causing a streamlined flow in the part of the main flow adjacent to the mouth of the by-pass passage in the inlet duct.

2. A pump according to claim 1, comprising valve means for regulating the flow of fluid through said by-pass passage.

3. A pump according to claim 1 comprising a rotary valve member extending across said by-pass passage, said member being journalled in said body portion and rotatable to vary both the minimum cross-sectional area of said by-pass passage, and the angle, relative to the direction of said main flow through said inlet, at which fluid is discharged through said by-pass passage into said inlet.

4. A centrifugal pump comprising an inlet for receiving a main flow of fluid into the pump, means defining a bypass passage for discharging fluid at an elevated pressure into said inlet and in counterflow to the minimum flow through said inlet to restrict said rnain flow, and directional means for varying the angle, relative to the direction of said main flow in said inlet, at which fluid is discharged into said inlet from said by-pass passage.

5. A pump in accordance with claim 4, comprising an adjustable unitary valve member which constitutes said directional means and includes means for varying the flow of fluid through said by-pass passage.

'6. A centrifugal pump comprising means defining a volute chamber, an inlet duct for directing a main flow of fluid into said volute chamber, an outlet duct for discharging the main flow of fluid from said volute chamber, and means defining a by-pass passage having a entrance positioned at a point part way around said volute chamber and an outlet in said inlet duct, said by-pass passage returning a partial flow of fluid into said inlet duct, said by-pass passage being oriented to direct the by-pass flow into the inlet duct substantially in opposition to the flow in said duct and at an acute angle thereto thereby causing a streamlined flow in the part of the main flow adjacent to said by-pass outlet.

7. A pump according to claim 6 wherein said by-pass passage is arranged at an angle, relative to said inlet duct, such that the fluid flow through said by-pass passage has said constricting action :upon said main flow through said inlet duct.

8. A pump according to claim 7 and comprising valve means in said by-pass passage for controlling the fluid flow therethrough, said valve means including means for varying the angle, relative to the main flow of fluid through said by-pass passage, at which fluid is discharged from said by-pass passage into said inlet.

9. A pump according to claim 7 comprising a rotary valve member arranged in said by-pass passage, rotation of said valve member being eifective to vary, simultaneously, the flow of fluid through said by-pass passage, and the angle, relative to the direction of said main flow through said inlet duct, at which fluid is discharged through said by-pass passage into said inlet duct.

10. A centrifugal pump comprising a pump housing defining a volute chamber, an inlet for receiving a main flow of fluid into said volute chamber and an outlet for discharging fluid from said volute chamber, means defining a by-pass passage having an entrance positioned part Way around said volute chamber and having a discharge end open to said inlet, said by-pass passage defining an angle with the inlet at which the direction of the fluid flow through the by-pass passage substantially opposes the flow direction of the fluid flow through the inlet, thereby restricting the fluid flow through. the inlet, pump means for pumping fluid through the housing, and directional means for varying the angle, relative to the direction of the main fluid flow through said inlet, at which fluid is discharged from said by-pass passage into said inlet.

11. A pump according to claim 10, comprising valve means for varying the flow of fluid through said by-pass passage.

References Cited by the Examiner UNITED STATES PATENTS 1,216,119 2/1917 Hinz 230115 1,467,331 9/ 1923 McDonald et al 103103 2,449,002 9/ 1948 Moody 10397 2,825,532 4/1958 Kadosch 230-122 2,865,297 12/ 1958 Cliborn 103-97 3,029,011 4/ 1962 Lewis 230-114 FOREIGN PATENTS 580,080 8/ 1924 France.

1,230,297 3/ 1960 France.

17,195 1909 Great Britain.

MARK NEWMAN, Primary Examiner.

LAURENCE V. EFNER, DONLEY J. STOCKING,

MARTIN P. SCHWADRON, Examiners.

J. C. MUNRO, W. L. FREEH, Assistant Examiners. 

1. A CENTRIFUGAL PUMP COMPRISING A PUMP HOUSING DEFINING THEREWITHIN A VOLUTE CHAMBER,AN INLET DUCT FOR A MAIN FLOW OF FLUID TO SAID VOLUTE CHAMBER AND AN OUTLET DUCE FROM SAID VOLUTE CHAMBER, SAID HOUSING FURTHER DEFINING A BY-PASS PASSAGE CONNECTING SAID VOLUTE CHAMBER WITH SAID INLET DUCT, AND PUMP MEANS WITHIN SAID VOLUTE CHAMBER FOR PUMPING FLUID THROUGH THE HOUSING, SAID BYPASS PASSAGE BEING ORIENTED TO DIRECT THE BY-PASS FLOW INTO THE INLET DUCT SUBSTANTIALLY IN OPPOSITION TO THE FLOW IN SAID DUCT AND AT AN ACUTE ANGLE THERETO CAUSING A STREAMLINED FLOW IN THE PART OF THE MAIN FLOW ADJACENT TO THE MOUTH OF THE BY-PASS PASSAGE IN THE INLET DUCT. 